1. Field of the Invention
The present invention relates generally to a method for forming on a substrate an arsenosilicate glass (ASG or AsSG) film with a cap film.
2. Related Art
Metal-oxide-semiconductor field effect transistors (MOSFETs) are fundamental switching devices to perform logic operations in large scale integrated circuits (LSIs). As the downsizing of MOSFETs progress, decrease in junction depth (Xj) and increase in doping concentration are indispensable in the scaling trend. FinFETs and Tri-gate FETs have fin structures for source/drain extension, and such devices require reduction of lateral resistance (or sheet resistance) of the source/drain extension regions to obtain larger drain current by scaling down of MOSFETs. Therefore, both shallow Xj (Xj is defined as the depth where dopant concentration is 5×1018/cm3) and low sheet resistance (Rs) of the source/drain extension regions are indispensable for further scaling down of MOSFETs. However, reducing Rs at shallow regions (e.g., Xj<10 nm) has not been successful. The above characteristics also are important to turn-on voltage-modulation by Ground-Plane (GP) technique for Tunnel Field-Effect Transistor (TFET).
Any discussion of problems and solutions in relation to the related art has been included in this disclosure solely for the purposes of providing a context for the present invention, and should not be taken as an admission that any or all of the discussion was known at the time the invention was made.